It is known that a glass plate may be cut from a glass blank by means of apparatus including a cuttting head supporting a cutting tool that is guided along a desired path. For example, it is disclosed in German Offenlegungsschrift No. 27 36 614, that the cutting tool may be supported on a rod connected to and extending from a piston which is movable in a cylinder in one direction to a working position when the cylinder is pressurized and in the opposite direction when the cylinder is vented to atmosphere after making a cut. The cylinder, it is disclosed, is connected to a source of compressed air. Also, it is disclosed in that publication that the cutting head is mounted on cross slides and that cutting head and the cutting tool which it supports is guided either by a template or by electronic control along a desired path.
It is not uncommon that during a cutting operation whereby a glass sheet may be cut from individual glass blanks conveyed seriatim to a working station that a glass blank may be incorrectly located with respect to the cutting head and the guided movement it is to follow, or the glass blank may have broken angles, or the glass blank may be too small to accommodate the full cutting operation resulting in further lowering movement of the cutting tool in the one direction from the working position and further guided movement in the lowered position. Thus, if the cutting tool for any reason, should drop from the surface of the glass blank, the pressure within the cylinder will maintain the cutting tool in the position to which it shall have dropped, and the cutting tool following the guided movement may run into the edge of the glass blank. Known prior art apparatus have no capability of retracting the cutting tool following such occurence which may result in injury to personnel and damage to the cutting tool.
Accordingly, it is a principal object and an important aspect of the present invention to provide capability in apparatus of the aforementioned type for immediate retraction of the cutting tool from a position below the working position at the cutting plane should the cutting tool for any reason leave the surface of the glass blank. According to the invention, the cutting tool will immediately retract to a waiting position.